15The glass slides were treated to provide for better adhesion
between the photographic emulsion and tissue sections. After being
soaked in dichromate solution for several hours, they were rinsed in
tap water, dipped in acetone and air dried. They were then irmersed
in a warm solution of 0.5 per cent gelatin and 0.05 per cent chrom-
alum in distilled water and dried at room temperature in a covered
staining dish (Boyd, 1955).

Gillman, J., C. Gilbert, T. Gillman and I. Spence 1946 A preliminary
report on hydrocephalus, spina bifida and other congenital
anomalies in the rat produced by trypan blue: The significance
of these results in the interpretation of congenital mal-
formations following maternal rubella. S. Afr. J. Med. Sci.,
13: 47-90.

Wislocki, G. B. 1921 Further experimental studies on fetal absorption.
III. The behavior of the fetal membranes and placenta of the
guinea pig toward trypan blue injected into the maternal blood
stream. IV. The behavior of the placenta and fetal membranes
of the rabbit toward trypan blue injected into the maternal
blood stream. In Carnegie Contributions to Embryology, 13:
89-101.